We derive the statistics of the signals generated by shape fluctuations of
large molecules studied by feedback tracking microscopy. We account for the
influence of intramolecular dynamics on the response of the tracking system,
and derive a general expression for the fluorescence autocorrelation function
that applies when those dynamics are linear. We show that tracking provides
enhanced sensitivity to translational diffusion, molecular size, heterogeneity
and long time-scale decays in comparison to traditional fluorescence
correlation spectroscopy. We demonstrate our approach by using a
three-dimensional tracking microscope to study genomic λ-phage DNA
molecules with various fluorescence label configurations.Comment: 11 pages, 5 figures, supplemental info:
http://minty.stanford.edu/papers/Publications/McHale10aSI.pd